Reformed coal production equipment

ABSTRACT

Reformed coal production equipment includes: a combustion furnace ( 124 ) for generating heated gas ( 11 ); a dry distillation gas supply pipe ( 101 ) for supplying dry distillation gas ( 14 ) generated at a dry distillation device to the combustion furnace; a vapor generator ( 125 ) to which a portion of the heated gas generated at the combustion furnace is supplied and which generates waste heat gas ( 13 ) by subjecting the heated gas to heat exchange; and a discharge pipe ( 52 ), a waste heat gas delivery pipe ( 54 ), a mixed gas delivery pipe ( 55 ), a blower ( 126 ), a mixed gas supply pipe ( 56 ), a mixed gas branching pipe ( 102 ), a flow rate adjustment valve ( 103 ), and a mixed gas communication pipe ( 104 ) supplying, to the dry distillation gas supply pipe, the waste heat gas and low-temperature heated gas ( 12 ) formed by indirectly heating dried coal by the heated gas at the dry distillation device ( 121 ).

TECHNICAL FIELD

The present invention relates to upgraded coal production equipment, and is particularly useful when used to upgrade coal of low rank (low-rank coal), such as brown coal or subbituminous coal, which is porous and has a high water content.

BACKGROUND ART

Coal of low rank (low-rank coal), such as brown coal or subbituminous coal, which is porous and has a high water content generates a low amount of heat per unit weight, and is therefore dried through a heating treatment to have improved amount of heat generation per unit weight.

As upgraded coal production equipment configured to perform such upgrade of low-rank coal, there is, for example, equipment including: an indirect-heating pyrolysis device which performs pyrolysis on low-rank coal by heating the low-rank coal indirectly by use of a heating gas; and a combustion furnace which generates the heating gas by combusting a pyrolysis gas generated in the pyrolysis device and supplied to the combustion furnace through a pyrolysis gas supply pipe.

The pyrolysis gas described above is composed of a low-boiling component. However, since the low-rank coal is processed under a relatively high temperature, the pyrolysis gas is accompanied by tar (pyrolysis oil) which is a high-boiling component. When the pyrolysis gas is cooled, the tar is attached to a wall surface of a duct or the like through which the pyrolysis gas flows. When a large amount of tar is attached, a problem might occur, such as clogging the duct. Hence, various techniques have been developed to remove the tar.

For example, Patent Document 1 given below discloses a decoking method for combusting and removing coke attached to the inside of a pipe by use of a gas which is obtained by adjusting air to have an oxygen concentration of 3 vol % to 21 vol % through dilution with water vapor or an inert gas, and which is also adjusted to have a temperature of 350° C. to 500° C.

Patent Document 2 given below discloses a method for performing a pyrolysis treatment on a processed object by using an external heating kiln. In this method, an oxygen-containing gas is supplied into an inner cylinder of the external heating kiln to combust a carbide of organic matter in the processed object and/or a combustible gas, which are produced by pyrolysis. Thereby, the temperature of a pyrolysis gas increases, so that liquefaction or solidification is prevented.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Application Publication No. Hei 5-188653 (see, e.g., paragraphs [0013], [0017], and the like)

Patent Document 2: Japanese Patent Application Publication No. 2004-3738 (see, e.g., paragraphs [0011], [0014], [0015], and the like)

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

To apply the decoking method described in Patent Document 1 to the upgraded coal production equipment described earlier, the decoking has to be performed with the pyrolysis device itself being stopped. Alternatively, two systems of ducts through which the pyrolysis device supplies the combustion furnace with a pyrolysis gas are provided, and the decoking has to be performed while stopping one of the systems. This entails decrease in operating rate of the equipment, size increase, and the like, causing increase in costs for producing upgraded coal. In other words, the tar cannot be removed efficiently.

By directly supplying the oxygen-concentration adjusted gas adjusted for its oxygen concentration to the pyrolysis gas supply pipe described earlier, tar produced during operation is combusted, so that attachment of the tar to the pyrolysis gas supply pipe can be suppressed. However, generating the oxygen-concentration adjusted gas from air or from an inert gas (nitrogen or water vapor) requires an apparatus specialized for that, and this increases costs for producing upgraded coal. Moreover, the oxygen-concentration adjusted gas has to be increased in temperature in advance in order for it to react with the tar. Thus, additional energy is needed. In sum, the tar cannot be removed efficiently.

In the method for performing a pyrolysis treatment on a processed object by using an external heating kiln described in Patent Document 2, the carbide itself of organic matter in the processed object produced by the pyrolysis is combusted. Thus, when this method is applied to the pyrolysis device of the upgraded coal production equipment, the production volume of the upgraded coal is lowered.

In view of the above, the present invention has been made to solve the problems described above, and has an objective of providing upgraded coal production equipment capable of efficient tar removal without lowering the production volume of upgraded coal.

Means for Solving the Problems

Upgraded coal production equipment according to a first aspect of the invention for solving the above problems is upgraded coal production equipment which includes drying means for drying coal, indirect-heating pyrolysis means for performing pyrolysis on the dried coal by indirectly heating the dried coal by use of a heating gas, and cooling means for cooling the coal subjected to the pyrolysis, and which is characterized in that the equipment comprises: heating gas generation means for generating the heating gas; pyrolysis gas supply means for supplying the heating gas generation means with a pyrolysis gas generated in the indirect-heating pyrolysis means; waste-heat gas generation means for receiving supply of part of the heating gas generated in the heating gas generation means and generating a waste-heat gas by subjecting the heating gas to heat exchange; and mixed gas supply means for supplying the pyrolysis gas supply means with the waste-heat gas and a low-temperature heating gas generated when the heating gas heats the coal indirectly in the indirect-heating pyrolysis means.

Upgraded coal production equipment according to a second aspect of the invention for solving the above problems is the upgraded coal production equipment according to the first aspect of the invention described above, characterized in that the equipment further comprises gas temperature measurement means, provided at the pyrolysis gas supply means, for measuring a gas temperature, and the mixed gas supply means includes gas flow rate adjustment means for adjusting a flow rate of the waste-heat gas and the low-temperature heating gas supplied to the pyrolysis gas supply means, and control means for controlling the gas flow rate adjustment means based on the gas temperature measured by the gas temperature measurement means.

EFFECT OF THE INVENTION

According to the upgraded coal production equipment of the present invention, the low-temperature heating gas and the waste-heat gas can be supplied to the pyrolysis gas supply means. Thereby, even if the pyrolysis gas is cooled in the pyrolysis gas supply means to face possible liquefaction or solidification of tar (pyrolysis oil), the low-temperature heating gas and the waste-heat gas make the oxygen concentration about 1 to 2%, and thereby the tar is oxidatively decomposed. As a result, the tar becomes light in weight and is thereby prevented from being attached to a wall surface of a duct or the like forming the pyrolysis gas supply means. Further, since a light gas generated when the tar becomes light in weight is combusted, the temperature of the pyrolysis gas rises, which can prevent attachment of tar to a wall surface of the duct or the like forming the pyrolysis gas supply means. The oxidative decomposition of the tar can be performed without stopping the device, and therefore the operating rate of the equipment can be improved compared to equipment which has to stop the device in order for the tar to be oxidatively decomposed. In other words, tar can be removed efficiently. Since the pyrolysis gas has almost the same temperature as the low-temperature heating gas and the waste-heat gas, preheating of the low-temperature heating gas and the waste-heat gas is unnecessary, which is energy-saving.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing the overall configuration of a main embodiment of upgraded coal production equipment according to the present invention.

MODE FOR CARRYING OUT THE INVENTION

An embodiment of upgraded coal production equipment according to the present invention is described.

Main Embodiment

Based on FIG. 1, a main embodiment of upgraded coal production equipment according to the present invention is described.

First, as shown in FIG. 1, low-rank coal 1 such as brown coal or subbituminous coal is supplied to a drying device 111 by a hopper or the like (not shown), the drying device 111 being drying means for drying the low-rank coal 1. An outlet opening of the drying device 111 communicates with an inlet opening 122 a of a pyrolysis device 121 configured to perform pyrolysis on dried coal 2. An outlet opening 122 b of the pyrolysis device 121 communicates with an inlet opening of a cooling device 131 being cooling means for cooling pyrolysis coal 3.

The pyrolysis device 121 has an inner cylinder 122 and an outer cylinder 123 surrounding the inner cylinder 122. The outer cylinder 123 is supplied with a heating gas 11 to be described later. Thereby, the dried coal 2 supplied into the inner cylinder 122 is indirectly heated and is subjected to pyrolysis, to generate the pyrolysis coal 3. In other words, the pyrolysis device 121 is an indirect-heating device, such as, e.g., an external heating kiln, in which a hot gas (heating gas) being a heat source does not come into direct contact with the low-rank coal 1. The pyrolysis device 121 forms indirect-heating pyrolysis means.

A gas exhaust port of the inner cylinder 122 of the pyrolysis device 121 communicates with a gas intake port of a combustion furnace 124 via a pyrolysis gas supply pipe 101. Thereby, a pyrolysis gas 14 containing gaseous tar (pyrolysis oil) generated by the pyrolysis is supplied to the gas intake port of the combustion furnace 124. The gas intake port of the combustion furnace 124 is also supplied with a fuel (not shown) such as a natural gas. The combustion furnace 124 generates the heating gas 11 by combusting the pyrolysis gas 14 and the fuel such as a natural gas. In other words, the combustion furnace 124 forms heating gas generation means. A gas exhaust port of the combustion furnace 124 communicates with a gas intake port of the outer cylinder 123 of the pyrolysis device 121 via a heating gas feed pipe 51.

The heating gas feed pipe 51 communicates with a gas intake port of a steam generator 125 via a heating gas branch pipe 53. The steam generator 125 forms waste-heat gas generation means for generating a waste-heat gas 13 through heat exchange between the heating gas 11 and water to thereby generate steam. A gas exhaust port of the steam generator 125 communicates with an exhaust pipe 52 to be described later via a waste-heat gas feed pipe 54.

A gas exhaust port of the outer cylinder 123 of the pyrolysis device 121 communicates with a gas intake port of an exhaust-gas treatment device 127 via the exhaust pipe 52, the exhaust-gas treatment device 127 being exhaust-gas purification means for purifying the waste-heat gas 13 and a low-temperature heating gas 12 which is generated when the heating gas 11 heats the inner cylinder 122. The low-temperature heating gas 12 and the waste-heat gas 13 are discharged to the outside of the system after undergoing the purification treatment in the exhaust-gas treatment device 127.

The exhaust pipe 52 communicates with a gas intake port of a blower 126 via a mixed gas feed pipe 55. A gas exhaust port of the blower 126 communicates with a gas intake port of the combustion furnace 124 via a mixed gas supply pipe 56. The mixed gas supply pipe 56 communicates with a mixed gas branch pipe 102. The mixed gas branch pipe 102 communicates with a mixed gas communication pipe 104 via a flow rate adjustment valve 103. The mixed gas communication pipe 104 communicates with the pyrolysis gas supply pipe 101.

The pyrolysis gas supply pipe 101 is provided with a gas temperature measurement instrument 105 which is gas temperature measurement means for measuring the temperature of a gas inside the pipe. The gas temperature measurement instrument 105 is connected to a control device 106 such that the measured gas temperature can be sent to the control device 106, the control device 106 being control means for controlling the valve position of the flow rate adjustment valve 103.

The exhaust pipe 52, the waste-heat gas feed pipe 54, the mixed gas feed pipe 55, the blower 126, the mixed gas supply pipe 56, the mixed gas branch pipe 102, the flow rate adjustment valve 103, the mixed gas communication pipe 104, and the like form mixed gas supply means.

In the upgraded coal production equipment according to this embodiment thus configured, when the low-rank coal 1 is charged into the hopper, the hopper supplies the low-rank coal 1 at a room temperature to the drying device 111 a predetermined amount at a time. The low-rank coal 1 supplied to the drying device 111 is removed of water and becomes the dried coal 2 by being heated up to about 200° C. by a drying combustion gas (about 150 to 300° C.) from a drying combustor (not shown). Then, the dried coal 2 is transferred into the inner cylinder 122 of the pyrolysis device 121. The dried coal 2 transferred to the pyrolysis device 121 is subjected to pyrolysis by being indirectly heated by the heating gas 11 (gas temperature: about 1050° C., oxygen concentration: about 2 to 3%) from the combustion furnace 124. Thereby, the dried coal 2 becomes the pyrolysis coal 3 as a result of removal of components such as the pyrolysis gas 14 containing gaseous tar, and the pyrolysis coal 3 is fed to the cooling device 131. The pyrolysis coal 3 fed to the cooling device 131 becomes upgraded coal 4 by being cooled down to about 50° C.

Meanwhile, the heating gas 11 (gas temperature: about 1050° C., oxygen concentration: about 2 to 3%) generated in the combustion furnace 124 is fed to the outer cylinder 123 of the pyrolysis device 121 via the heating gas feed pipe 51. The heating gas 11 used inside the outer cylinder 123 to heat the inner cylinder 122 becomes the low-temperature heating gas 12 (gas temperature: about 350° C., oxygen concentration: about 2 to 3%). The low-temperature heating gas 12 is fed to the exhaust pipe 52. Meanwhile, the heating gas 11 is also fed to the steam generator 125 via the heating gas feed pipe 51 and the heating gas branch pipe 53. The heating gas 11 used in the steam generator 125 for generation of water vapor becomes the waste-heat gas 13 (gas temperature: about 350° C., oxygen concentration: about 2 to 3%). The waste-heat gas 13 is fed to the exhaust pipe 52 via the waste-heat gas feed pipe 54.

Part of the low-temperature heating gas 12 and the waste-heat gas 13 is supplied to the exhaust-gas treatment device 127. The low-temperature heating gas 12 and the waste-heat gas 13 undergo the purification treatment in the exhaust-gas treatment device 127 and are then discharged to the outside of the system. The rest of the low-temperature heating gas 12 and the waste-heat gas 13 (gas temperature: about 350° C., oxygen concentration: about 2 to 3%) is fed to the blower 126 via the mixed gas feed pipe 55.

Part of the low-temperature heating gas 12 and the waste-heat gas 13 fed to the blower 126 is supplied to the combustion furnace 124 via the mixed gas supply pipe 56. The rest of the low-temperature heating gas 12 and the waste-heat gas 13 (gas temperature: about 350° C., oxygen concentration: about 2 to 3%) fed to the blower 126 is supplied to the pyrolysis gas supply pipe 101 via the mixed gas branch pipe 102, the flow rate adjustment valve 103, and the mixed gas communication pipe 104.

The valve position of the flow rate adjustment valve 103 is controlled by the control device 106 based on the gas temperature measured by the gas temperature measurement instrument 105. For example, the control device 106 adjusts the flow rate adjustment valve 103 by opening it to increase the aperture when the gas temperature measured by the gas temperature measurement instrument 105 is equal to or higher than 400° C., and adjusts the flow rate adjustment valve 103 by narrowing it when the gas temperature exceeds 550° C. Thereby, the low-temperature heating gas 12 and the waste-heat gas 13 (oxygen concentration: about 2 to 3%) are mixed with the pyrolysis gas 14 (gas temperature: about 400° C., oxygen concentration: about 0%), and this mixed gas has an oxygen concentration adjusted to about 1 to 2%. As a result, gaseous tar (pyrolysis oil) is oxidatively decomposed (decoking) to become light in weight, and thereby attachment of the tar to the pyrolysis gas supply pipe 101 can be prevented. The tar is reduced in weight to become a light gas, and this light gas is combusted. Thus, decrease in the gas temperature is prevented. Thereby, attachment of the tar to the pyrolysis gas supply pipe 101 can be prevented. Specifically, the decoking is performed just when the tar is about to be attached to the inner wall surface of the pyrolysis gas supply pipe 101 by adjustment of the amount of the low-temperature heating gas 12 and the waste-heat gas 13 supplied to the pyrolysis gas supply pipe 101 based on the gas temperature inside the pyrolysis gas supply pipe 101. Hence, the tar can be efficiently removed.

Thus, according to the upgraded coal production equipment according to this embodiment, by supplying the low-temperature heating gas 12 and the waste-heat gas 13 into the pyrolysis gas supply pipe 101, the oxygen concentration of the gases 12, 13, 14 in the pyrolysis gas supply pipe 101 is adjusted to about 1 to 2%, so that tar contained in the pyrolysis gas 14 (pyrolysis oil) is oxidatively decomposed (decoking) to become light in weight. Thereby, attachment of the tar to the pyrolysis gas supply pipe 101 can be prevented.

Moreover, since a light gas generated when the tar becomes light in weight is combusted, the temperature of the pyrolysis gas 14 rises, which can prevent attachment of the pyrolysis oil to a wall surface of the pyrolysis gas supply pipe 101 and the like. Since the pyrolysis gas 14 has almost the same temperature as the low-temperature heating gas 12 and the waste-heat gas 13, preheating of the low-temperature heating gas 12 and the waste-heat gas 13 is unnecessary, which is energy-saving. Furthermore, since decoking can be performed to remove tar without stopping the device, the operating rate of the equipment can be improved compared to equipment which has to stop the device to decoke the device for tar removal. In other words, tar can be removed efficiently.

INDUSTRIAL APPLICABILITY

The upgraded coal production equipment according to the present invention can remove tar efficiently without lowering the production volume of upgraded coal, and can therefore be utilized significantly beneficially in various industries.

EXPLANATION OF REFERENCE NUMERALS

1 low-rank coal

2 dried coal

3 pyrolysis coal

4 upgraded coal

11 heating gas

12 low-temperature heating gas

13 waste-heat gas

14 pyrolysis gas

51 heating gas feed pipe

52 exhaust pipe

53 heating gas branch pipe

54 waste-heat gas feed pipe

55 mixed gas feed pipe

56 mixed gas supply pipe

101 pyrolysis gas supply pipe

102 mixed gas branch pipe

103 flow rate adjustment valve

104 mixed gas communication pipe

105 gas temperature measurement instrument

106 control device

111 drying device

121 pyrolysis device

122 inner cylinder

123 outer cylinder

124 combustion furnace

125 steam generator

126 blower

127 exhaust-gas treatment device

131 cooling device 

1. Upgraded coal production equipment including drying means for drying coal, indirect-heating pyrolysis means for performing pyrolysis on the dried coal by indirectly heating the dried coal by use of a heating gas, and cooling means for cooling the coal subjected to the pyrolysis, characterized in that the equipment comprises: heating gas generation means for generating the heating gas; pyrolysis gas supply means for supplying the heating gas generation means with a pyrolysis gas generated in the indirect-heating pyrolysis means; waste-heat gas generation means for receiving supply of part of the heating gas generated in the heating gas generation means and generating a waste-heat gas by subjecting the heating gas to heat exchange; and mixed gas supply means for supplying the pyrolysis gas supply means with the waste-heat gas and a low-temperature heating gas generated when the heating gas heats the coal indirectly in the indirect-heating pyrolysis means.
 2. The upgraded coal production equipment according to claim 1, characterized in that p1 the equipment further comprises gas temperature measurement means, provided at the pyrolysis gas supply means, for measuring a gas temperature, and the mixed gas supply means includes gas flow rate adjustment means for adjusting a flow rate of the waste-heat gas and the low-temperature heating gas supplied to the pyrolysis gas supply means, and control means for controlling the gas flow rate adjustment means based on the gas temperature measured by the gas temperature measurement means. 